Automatic high-pressure alarm



(No Model.)

0! W. BEMISH. AUTOMATIC HIGH PRESSURE ALARM.

No. 594,514. Patented Nov: 30,1897.

QW/IVTLIESSES K 5. 2544M A ltorney UNITED STATES PATENT @rrrcn.

CHARLES XV. BEMISH, Oh TACOMA, W'ASHINGTON.

AUTOMATIC HIGH PRESSURE ALARM.

SPECIFICATION forming part of Letters Patent No. 594,514, dated November30, 1897.

Application filed January 9 189 '7.

To aZZ whom it may concern.-

Be it known that 1, CHARLES W. Bmnsn, a citizen of the United States,residing at Tacoma, in the county of Pierce and State of Washington,have invented certain new and useful Improvements in Safety Steam-GageAttachments; and I do hereby declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

The object of my invention is to prevent the possibility of accidentconsequent upon the explosion of a boiler or the like, due to thesticking or wedgin g of the safety or pop valve, by apprising theattendant by an automatic alarm of the excess of pressure within theboiler over that provided for by the setting of the safety-valve.

To the accomplishment of this object my invention consists in providinga pressurega-ge attached to a boiler with automatic alarm mechanism,which will be brought into operation as soon as the pressure hasexceeded a predetermined limit.

In the accompanying drawings, forming a part of this specification,Figure l is an elevation of my safety-gage and alarm mechanism complete.Fig. 2 is a detail view of the contact-plug.

Referring to the numerals on the drawings, 1 indicates a steamgage ofordinary construction, connected with a boiler 2 by a gagetube 3, asshown.

t indicates the hand or index-pointer, pivoted upon a post 5 andconnected with pressure-controlled actuating mechanism well known in theart and not illustrated. The hand 4 is designed, as usual, to traversethe face of a dial 6, upon which is mounted degrees of pressure fromzero to one hundred and fifty or higher.

My invention consists specifically in providing the steam-gage with whatI shall term a safety or alarm dial 7, surrounding the dial 6 andprovided immediately beyond each of the scale-figures upon the dial withthe perforations 8, internally screw-threaded and designed for thereception of a contactplug 9, which is illustrated in Fig. l and is anordinary brass contact-plug wound near Serial No. 618,550. (llo model.)

its base with one of the wires 10 of the alarmcircuit 11. Immediatelybelow the head of the plug 9 I provide suitable insulation 11, aroundwhich is wound a second wire 13 of the alarmcircuit. It is evident thatthis plug may be located in the apertures S,which correspond with thepressure at which the safety-valve is set to open, and as soon as thehand has passed the safety-point it will in the event of the failure ofthe safety-valve come in contact with the wire 13, wound upon theinsulation of the plug. The alarm-circuit will now be closed through thehand Al, its post 5, the metallic parts of the gage, including thesafety-dial 7, and through the plug and connected wire 10 of thealarm-circuit. Any suitable mechanism may be located within thealarm-circuit 11as, for instance, the usual electric bell 1i.

Ordinarily the safety-point is several degrees in advance of thebursting-point of the boiler, and it is therefore desirable that theindex-pointer or hand shall remain in contact with the plug for soundingthe alarm continuously while the pressure is raising beyond thesafety-point. To accomplish this prolonged contact between the hand andplug,

I mount the former edgewise upon the dial,

so as to permit it to yield, as indicated in the drawings, in order topermit considerable advance movement of the post 5 without breaking thecontact between the hand and the plug.

The particular form of alarm is not an essential feature of myinvention, but it is ob Vious that any alarm mechanism which would bebrought into actuation by the opening or closing of the circuit could beemployed.

It is obvious that upon failure of the safetyvalve to act at apredetermined pressure the safety-gage will cause the alarm-circuit tobe closed and an alarm will be sounded in the engine-room or oflice orwherever desired. The plugs being detachable may be set in any of theapertures S, accordingly as the safetyvalve is set at a high or lowpressure.

I do not desire to limitmyself to the details of construction hereinshown and described, but reserve to myself the right to change, modify,or vary such details within the scope of my invention.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1. In a device of the character described, the combination with apressure-gage provided with a non-conductive dial and with a metallicalarm-dial provided with graduated apertures, of a contact-plug, analarm-circuit having both terminals wrapped upon the plug, one of saidterminals being insulated there from, and a hand movable over the faceof the gage and mounted edgewise, said hand being designed to makecontact with the insulated terminals of the alarm-circuit and to holdsaid circuit closed during a predetermined movcment of the hand,substantially as specified.

2. In a device of the character described, the combination with apressure-gage provided with a non-conductive dial and with a metallicalarm-d ial surrounding the same provided with graduated apertures, of acontactplug designed to be inserted in the apertures, an alarm-circuithaving its terminals wrapped upon and insulated from the plug, and ahand mounted edgewise and movable over the dial in a manner to makecontact between the terminals of the alarm-circuit and to retain saidcircuit closed during a predetermined movement of the hand, the locationof the contact-plug upon the alarm-dial and the provision of anon-conductive dial serving to prevent magnetizing of the movable partsof the gage, substantially as specificd.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

OIIA tIilflS \V. HEMISII.

Witnesses:

A. 13. OowLns, W. R. Lnwrs.

